Zoom optical system, optical apparatus and method for manufacturing the zoom optical system

ABSTRACT

A zoom optical system (ZL) comprises, in order from an object: a first lens group (G 1 ) having positive refractive power; an intermediate group (GM) including at least one lens group and having negative refractive power as a whole; an intermediate side lens group (GRP 1 ) having positive refractive power; a subsequent side lens group (GRP 2 ) having positive refractive power; and a subsequent group (GR) including at least one lens group. The subsequent side lens group (GRP 2 ) moves upon focusing. A following conditional expression is satisfied: 
       2.5&lt; f 1/ fRP 1&lt;5.0         where,   f1 denotes a focal length of the first lens group (G 1 ), and   fRP1 denotes a focal length of the intermediate side lens group (GRP 1 ).

TECHNICAL FIELD

The present invention relates to a zoom optical system, an opticalapparatus using the same and a method for manufacturing the zoom opticalsystem.

TECHNICAL BACKGROUND

A zoom optical system suitable for photographic cameras, electronicstill cameras, video cameras, and the like has conventionally beenproposed (see, for example, Patent Document 1). Optical performance ofsuch a conventional zoom optical system has been insufficient.

PRIOR ARTS LIST Patent Document

Patent Document 1: Japanese Laid-Open Patent Publication No. H4-293007(A)

SUMMARY OF THE INVENTION

A zoom optical system according to the present invention comprises, inorder from an object: a first lens group having positive refractivepower; an intermediate group including at least one lens group andhaving negative refractive power as a whole; an intermediate side lensgroup having positive refractive power; a subsequent side lens grouphaving positive refractive power; and a subsequent group including atleast one lens group. Upon zooming, distances between the first lensgroup and the intermediate group, between the intermediate group and theintermediate side lens group, between the intermediate side lens groupand the subsequent side lens group, and between the subsequent side lensgroup and the subsequent group change. The subsequent side lens groupmoves upon focusing. A following conditional expression is satisfied:

2.5<f1/fRP1<5.0

where,

f1 denotes a focal length of the first lens group, and

fRP1 denotes a focal length of the intermediate side lens group.

An optical apparatus according to the present invention comprises thezoom optical system described above.

A method for manufacturing a zoom optical system according to thepresent invention is a method for manufacturing a zoom optical systemwhich comprises, in order from an object: a first lens group havingpositive refractive power; an intermediate group including at least onelens group and having negative refractive power as a whole; anintermediate side lens group having positive refractive power; asubsequent side lens group having positive refractive power; and asubsequent group including at least one lens group, the methodcomprising a step of arranging the lens groups in a lens barrel so that:upon zooming, distances between the first lens group and theintermediate group, between the intermediate group and the intermediateside lens group, between the intermediate side lens group and thesubsequent side lens group, and between the subsequent side lens groupand the subsequent group change; the subsequent side lens group movesupon focusing; and a following conditional expression is satisfied:

2.5<f1/fRP1<5.0

-   -   where,    -   f1 denotes a focal length of the first lens group, and    -   fRP1 denotes a focal length of the intermediate side lens group.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a lens configuration of a zoom opticalsystem according to Example 1 of the present embodiment.

FIG. 2A is a graph showing various aberrations of the zoom opticalsystem according to Example 1 upon focusing on infinity in a wide angleend state, and FIG. 2B is a meridional lateral aberration graph in acase where blur correction is performed for the roll blur of 0.30°.

FIG. 3 is a graph showing various aberrations of the zoom optical systemaccording to Example 1 upon focusing on infinity in an intermediatefocal length state.

FIG. 4A is a graph showing various aberrations of the zoom opticalsystem according to Example 1 upon focusing on infinity in a telephotoend state, and FIG. 4B is a meridional lateral aberration graph in acase where blur correction is performed for the roll blur of 0.20°.

FIGS. 5A, 5B, and 5C are graphs showing various aberrations of the zoomoptical system according to Example 1 upon focusing on a short distantobject, respectively in the wide angle end state, the intermediate focallength state, and the telephoto end state.

FIG. 6 is a diagram illustrating a lens configuration of a zoom opticalsystem according to Example 2 of the present embodiment.

FIG. 7A is a graph showing various aberrations of the zoom opticalsystem according to Example 2 upon focusing on infinity in the wideangle end state, and FIG. 7B is a meridional lateral aberration graph ina case where blur correction is performed for the roll blur of 0.30°.

FIG. 8 is a graph showing various aberrations of the zoom optical systemaccording to Example 2 upon focusing on infinity in the intermediatefocal length state.

FIG. 9A is a graph showing various aberrations of the zoom opticalsystem according to Example 2 upon focusing on infinity in the telephotoend state, and FIG. 9B is a meridional lateral aberration graph in acase where blur correction is performed for the roll blur of 0.20°.

FIGS. 10A, 10B, and 10C are graphs showing various aberrations of thezoom optical system according to Example 2 upon focusing on a shortdistant object, respectively in the wide angle end state, theintermediate focal length state, and the telephoto end state.

FIG. 11 is a diagram illustrating a lens configuration of a zoom opticalsystem according to Example 3 of the present embodiment.

FIG. 12A is a graph showing various aberrations of the zoom opticalsystem according to Example 3 upon focusing on infinity in the wideangle end state, and FIG. 12B is a meridional lateral aberration graphin a case where blur correction is performed for the roll blur of 0.30°.

FIG. 13 is a graph showing various aberrations of the zoom opticalsystem according to Example 3 upon focusing on infinity in theintermediate focal length state.

FIG. 14A is a graph showing various aberrations of the zoom opticalsystem according to Example 3 upon focusing on infinity in the telephotoend state, and FIG. 14B is a meridional lateral aberration graph in acase where blur correction is performed for the roll blur of 0.20°.

FIGS. 15A, 15B, and 15C are graphs showing various aberrations of thezoom optical system according to Example 3 upon focusing on a shortdistant object, respectively in the wide angle end state, theintermediate focal length state, and the telephoto end state.

FIG. 16 is a diagram illustrating a lens configuration of a zoom opticalsystem according to Example 4 of the present embodiment.

FIG. 17A is a graph showing various aberrations of the zoom opticalsystem according to Example 4 upon focusing on infinity in the wideangle end state, and FIG. 17B is a meridional lateral aberration graphin a case where blur correction is performed for the roll blur of 0.30°.

FIG. 18 is a graph showing various aberrations of the zoom opticalsystem according to Example 4 upon focusing on infinity in theintermediate focal length state.

FIG. 19A is a graph showing various aberrations of the zoom opticalsystem according to Example 4 upon focusing on infinity in the telephotoend state, and FIG. 19B is a meridional lateral aberration graph in acase where blur correction is performed for the roll blur of 0.20°.

FIGS. 20A, 20B, and 20C are graphs showing various aberrations of thezoom optical system according to Example 4 upon focusing on a shortdistant object, respectively in the wide angle end state, theintermediate focal length state, and the telephoto end state.

FIG. 21 is a diagram illustrating a lens configuration of a zoom opticalsystem according to Example 5 of the present embodiment.

FIG. 22A is a graph showing various aberrations of the zoom opticalsystem according to Example 5 upon focusing on infinity in the wideangle end state, and FIG. 22B is a meridional lateral aberration graphin a case where blur correction is performed for the roll blur of 0.30°.

FIG. 23 is a graph showing various aberrations of the zoom opticalsystem according to Example 5 upon focusing on infinity in theintermediate focal length state.

FIG. 24A is a graph showing various aberrations of the zoom opticalsystem according to Example 5 upon focusing on infinity in the telephotoend state, and FIG. 24B is a meridional lateral aberration graph in acase where blur correction is performed for the roll blur of 0.20°.

FIGS. 25A, 25B, and 25C are graphs showing various aberrations of thezoom optical system according to Example 5 upon focusing on a shortdistant object, respectively in the wide angle end state, theintermediate focal length state, and the telephoto end state.

FIG. 26 is a diagram illustrating a lens configuration of a zoom opticalsystem according to Example 6 of the present embodiment.

FIG. 27A is a graph showing various aberrations of the zoom opticalsystem according to Example 6 upon focusing on infinity in the wideangle end state, and FIG. 27B is a meridional lateral aberration graphin a case where blur correction is performed for the roll blur of 0.30°.

FIG. 28 is a graph showing various aberrations of the zoom opticalsystem according to Example 6 upon focusing on infinity in theintermediate focal length state.

FIG. 29A is a graph showing various aberrations of the zoom opticalsystem according to Example 6 upon focusing on infinity in the telephotoend state, and FIG. 29B is a meridional lateral aberration graph in acase where blur correction is performed for the roll blur of 0.20°.

FIGS. 30A, 30B, and 30C are graphs showing various aberrations of thezoom optical system according to Example 6 upon focusing on a shortdistant object, respectively in the wide angle end state, theintermediate focal length state, and the telephoto end state.

FIG. 31 is a diagram illustrating a configuration of a camera comprisingthe zoom optical system according to the present embodiment.

FIG. 32 is a flowchart illustrating a method for manufacturing the zoomoptical system according to the present embodiment.

DESCRIPTION OF THE EMBODIMENTS

A zoom optical system and an optical apparatus according to the presentembodiment are described below with reference to the drawings. Asillustrated in FIG. 1, a zoom optical system ZL(1) as an example of azoom optical system (zoom lens) ZL according to the present embodimentcomprises, in order from an object: a first lens group G1 havingpositive refractive power; an intermediate group GM (second lens groupG2) including at least one lens group and having negative refractivepower as a whole; an intermediate side lens group GRP1 (third lens groupG3) having positive refractive power; a subsequent side lens group GRP2(fourth lens group G4) having positive refractive power; and asubsequent group GR (fifth lens group G5) including at least one lensgroup. Upon zooming, distances between the first lens group G1 and theintermediate group GM, between the intermediate group GM and theintermediate side lens group GRP1, between the intermediate side lensgroup GRP1 and the subsequent side lens group GRP2, and between thesubsequent side lens group GRP2 and the subsequent group GR change. Thesubsequent side lens group GRP2 moves as a focusing lens group uponfocusing.

The zoom optical system ZL according to the present embodiment may alsobe a zoom optical system ZL(2) illustrated in FIG. 6, a zoom opticalsystem ZL(3) illustrated in FIG. 11, a zoom optical system ZL(4)illustrated in FIG. 16, a zoom optical system ZL(5) illustrated in FIG.21, or a zoom optical system ZL(6) illustrated in FIG. 26. The zoomoptical systems ZL(2), ZL(3), and ZL(4) respectively illustrated inFIGS. 6, 11, and 16 have the same configuration as the zoom opticalsystem ZL(1) illustrated in FIG. 1. In the zoom optical system ZL(5)illustrated in FIG. 21, the intermediate group GM (second lens groupG2), the intermediate side lens group GRP1 (third lens group G3), andthe subsequent side lens group GRP2 (fourth lens group G4) have the sameconfigurations as those in the zoom optical system ZL(1) illustrated inFIG. 1. The subsequent group GR consists of the fifth lens group G5 anda sixth lens group G6. In the zoom optical system ZL(6) illustrated inFIG. 26, the intermediate group GM consists of the second lens group G2and the third lens group G3, the intermediate side lens group GRP1consists of the fourth lens group G4, the subsequent side lens groupGRP2 consists of the fifth lens group G5, and the subsequent group GRconsists of the sixth lens group G6.

The zoom optical system ZL according to the present embodiment comprisesat least five lens groups, and the distances among the lens groupschange upon zooming. Thus, successful aberration correction can beachieved upon zooming. Focusing is performed with the subsequent sidelens group GRP2 serving as the focusing lens group, and thus thefocusing lens group can be small and light weight.

An aperture stop is preferably disposed to an object side or an imageside of the intermediate side lens group GRP1. The aperture stop may bedisposed between lenses forming the intermediate side lens group GRP1.

The intermediate group GM preferably comprises negative refractive poweras a whole from the wide angle end state to the telephoto end state. Forexample, the intermediate group GM may consist of one lens group havingnegative refractive power, or may consist of two lens groups each havingnegative refractive power. For example, the intermediate group GM mayconsist of two lens groups including, in order from the object, a lensgroup having positive refractive power and a lens group having negativerefractive power, or may consist of two lens groups including, in orderfrom the object, a lens group having negative refractive power and alens group having positive refractive power.

The subsequent group GR preferably comprises negative or positiverefractive power as a whole. For example, the subsequent group GR mayconsist of one lens group having negative refractive power, or mayconsist of two lens groups each having negative refractive power.

A plurality of lens groups may be configured to move along the samemovement locus upon zooming. Preferably, at least one lens group in theintermediate side lens group GRP1 and at least one lens group in thesubsequent group GR are configured to move along the same movementlocus. More preferably, at least one lens group in the first lens groupG1, at least one lens group in the intermediate side lens group GRP1,and at least one lens group in the subsequent group GR are configured tomove along the same movement locus.

The zoom optical system ZL according to the present embodiment havingthe configuration described above satisfies the following conditionalexpression.

2.5<f1/fRP1<5.0  (1)

where,

f1 denotes a focal length of the first lens group G1, and

fRP1 denotes a focal length of the intermediate side lens group GRP1.

The conditional expression (1) is for setting an appropriate range of aratio between the focal lengths of the first lens group G1 and theintermediate side lens group GRP1. Variation of various aberrationsincluding the spherical aberration can be prevented upon zooming whenthe conditional expression (1) is satisfied.

A value higher than the upper limit value of the conditional expression(1) leads to large refractive power of the intermediate side lens groupGRP1, rendering variation of various aberrations including the sphericalaberration upon zooming difficult to prevent. The effects of the presentembodiment can be more effectively guaranteed with the upper limit valueof the conditional expression (1) set to be 4.7. To more effectivelyguarantee the effects of the present embodiment, the upper limit valueof the conditional expression (1) is preferably set to be 4.4.

A value lower than the lower limit value of the conditional expression(1) leads to large refractive power of the first lens group G1,rendering various aberrations including the spherical aberration uponzooming difficult to correct. The effects of the present embodiment canbe more effectively guaranteed with the lower limit value of theconditional expression (1) set to be 2.7. To more effectively guaranteethe effects of the present embodiment, the lower limit value of theconditional expression (1) is preferably set to be 2.9.

In the zoom optical system according to the present embodiment, theintermediate group GM preferably comprises a vibration-proof lens groupmovable to have a component in a direction orthogonal to the opticalaxis to correct image blur. This effectively prevents the performancefrom being compromised by camera shake correction.

The zoom optical system according to the present embodiment preferablysatisfies the following conditional expression (2).

2.9<f1/(−fMt)<5.5  (2)

where,

fMt denotes a focal length of the intermediate group GM in the telephotoend state.

The conditional expression (2) is for setting an appropriate range of aratio between the focal lengths of the first lens group G1 and theintermediate group GM in the telephoto end state. Variation of variousaberrations including the spherical aberration can be prevented uponzooming when the conditional expression (2) is satisfied.

A value higher than the upper limit value of the conditional expression(2) leads to large refractive power of the intermediate group GM,rendering variation of various aberrations including the sphericalaberration upon zooming difficult to prevent. The effects of the presentembodiment can be more effectively guaranteed with the upper limit valueof the conditional expression (2) set to be 5.2. To more effectivelyguarantee the effects of the present embodiment, the upper limit valueof the conditional expression (2) is preferably set to be 4.9.

A value lower than the lower limit value of the conditional expression(2) leads to large refractive power of the first lens group G1,rendering various aberrations including the spherical aberration uponzooming difficult to correct. The effects of the present embodiment canbe more effectively guaranteed with the lower limit value of theconditional expression (2) set to be 3.1. To more effectively guaranteethe effects of the present embodiment, the lower limit value of theconditional expression (2) is preferably set to be 3.3.

The zoom optical system according to the present embodiment preferablyhas a configuration in which the first lens group G1 moves toward theobject upon zooming from the wide angle end state to the telephoto endstate. With this configuration, a short total length of the lenses inthe wide angle end state can be achieved, whereby a small size of thezoom optical system can be achieved.

The zoom optical system according to the present embodiment preferablycomprises the subsequent side lens group GRP2 having at least one lenshaving positive refractive power and at least one lens having negativerefractive power. With this configuration, variation of variousaberrations including the spherical aberration can be prevented uponfocusing.

The zoom optical system according to the present embodiment preferablysatisfies the following conditional expression (3).

0.2<fP/(−fN)<0.8  (3)

where,

fP denotes a focal length of a lens with largest positive refractivepower in the subsequent side lens group GRP2, and

fN denotes a focal length of a lens with largest negative refractivepower in the subsequent side lens group GRP2.

The conditional expression (3) is for defining an appropriate range of aratio between the focal lengths of the lens with the largest positiverefractive power in the subsequent side lens group GRP2 and the lenswith the largest negative refractive power in the subsequent side lensgroup GRP2. Variation of various aberrations including the sphericalaberration can be prevented upon focusing when the conditionalexpression (3) is satisfied.

A value higher than the upper limit value of the conditional expression(3) leads to large refractive power of the lens with the largestnegative refractive power in the subsequent side lens group GRP2,rendering variation of various aberrations including the sphericalaberration upon focusing difficult to prevent. The effects of thepresent embodiment can be more effectively guaranteed with the upperlimit value of the conditional expression (3) set to be 0.75. To moreeffectively guarantee the effects of the present embodiment, the upperlimit value of the conditional expression (3) is preferably set to be0.70.

A value lower than the lower limit value of the conditional expression(3) leads to large refractive power of the lens with the largestpositive refractive power in the subsequent side lens group GRP2,rendering variation of various aberrations including the sphericalaberration upon focusing difficult to prevent. The effects of thepresent embodiment can be more effectively guaranteed with the lowerlimit value of the conditional expression (3) set to be 0.25. To moreeffectively guarantee the effects of the present embodiment, the lowerlimit value of the conditional expression (3) is preferably set to be0.30.

The zoom optical system according to the present embodiment preferablycomprises the first lens group G1 including, in order from an object: a1-1st lens having positive refractive power; a 1-2nd lens havingnegative refractive power; and a 1-3rd lens having positive refractivepower. With this configuration, the spherical aberration and a chromaticaberration can be successfully corrected.

The zoom optical system according to the present embodiment preferablysatisfies the following conditional expression (4).

0.85<nP/nN<1.00  (4)

where,

nP denotes a refractive index of a lens with largest positive refractivepower in the first lens group G1, and

nN denotes a refractive index of a lens with largest negative refractivepower in the first lens group G1.

The conditional expression (4) is for defining an appropriate range of aratio between the refractive indices of the lens with the largestpositive refractive power in the first lens group G1 and the lens withthe largest negative refractive power in the first lens group G1.Various aberrations including the spherical aberration can besuccessfully corrected when the conditional expression (4) is satisfied.

A value higher than the upper limit value of the conditional expression(4) leads to a small refractive index of the lens with the largestnegative refractive power in the first lens group G1, rendering variousaberrations including the spherical aberration difficult to correct. Theeffects of the present embodiment can be more effectively guaranteedwith the upper limit value of the conditional expression (4) set to be0.98. To more effectively guarantee the effects of the presentembodiment, the upper limit value of the conditional expression (4) ispreferably set to be 0.96.

A value lower than the lower limit value of the conditional expression(4) leads to a small refractive index of the lens with the largestpositive refractive power in the first lens group G1, leading toextremely large spherical aberration that is difficult to correct. Theeffects of the present embodiment can be more effectively guaranteedwith the lower limit value of the conditional expression (4) set to be0.86. To more effectively guarantee the effects of the presentembodiment, the lower limit value of the conditional expression (4) ispreferably set to be 0.87.

The zoom optical system according to the present embodiment preferablysatisfies the following conditional expression (5).

2.25<νP/νN<2.90  (5)

where,

νP denotes an Abbe number of the lens with the largest positiverefractive power in the first lens group G1, and

νN denotes an Abbe number of the lens with the largest negativerefractive power in the first lens group G1.

The conditional expression (5) is for defining an appropriate range of aratio between the Abbe numbers of the lens with the largest positiverefractive power in the first lens group G1 and the lens with thelargest negative refractive power in the first lens group G1. Thechromatic aberration can be successfully corrected when the conditionalexpression (5) is satisfied.

A value higher than the upper limit value of the conditional expression(5) leads to a small Abbe number of the lens with the largest negativerefractive power in the first lens group G1, resulting in an extremelylarge chromatic aberration that is difficult to correct. The effects ofthe present embodiment can be more effectively guaranteed with the upperlimit value of the conditional expression (5) set to be 2.85. To moreeffectively guarantee the effects of the present embodiment, the upperlimit value of the conditional expression (5) is preferably set to be2.80.

A value lower than the lower limit value of the conditional expression(5) leads to a small Abbe number of the lens with the largest positiverefractive power in the first lens group G1, leading to extremely largechromatic aberration that is difficult to correct. The effects of thepresent embodiment can be more effectively guaranteed with the lowerlimit value of the conditional expression (5) set to be 2.30. To moreeffectively guarantee the effects of the present embodiment, the lowerlimit value of the conditional expression (5) is preferably set to be2.35.

The optical apparatus according to the present embodiment comprises thezoom optical system with the configuration described above. A camera(optical apparatus) including the zoom optical system ZL is described,as a specific example, with reference to FIG. 31. This camera 1 is adigital camera including the zoom optical system according to thepresent embodiment serving as an imaging lens 2 as illustrated in FIG.31. In the camera 1, the imaging lens 2 collects light from an object(subject) (not illustrated), and then the light reaches an image sensor3. Thus, an image based on the light from the subject is formed with theimage sensor 3 to be stored as a subject image in a memory (notillustrated). In this manner, the photographer can capture an image ofthe subject with the camera 1. The camera may be a mirrorless camera, ormay be a single lens reflex camera having a quick return mirror.

With the configuration described above, the camera 1 comprising the zoomoptical system ZL serving as the imaging lens 2 can have the subsequentside lens group GRP2 serving as the focusing lens group that is smalland light weight, and thus quick and quiet AF (Auto Focus) can beachieved without using a large barrel. Furthermore, with thisconfiguration, variation of aberrations upon zooming from the wide angleend state to the telephoto end state, as well as variation ofaberrations upon focusing on a short distant object from an infinitedistant object can be successfully prevented, whereby excellent opticalperformance can be achieved.

Next, a method for manufacturing the zoom optical system ZL describedabove is described with reference to FIG. 32. First of all, in orderfrom the object, the first lens group G1 having positive refractivepower, the intermediate group GM including at least one lens group andhaving negative refractive power, the intermediate side lens group GRP1having positive refractive power, the subsequent side lens group GRP2having positive refractive power, and the subsequent group GR includingat least one lens group are arranged in a barrel (step ST1). The lensgroups are arranged in the lens barrel so that, upon zooming, thedistances between the first lens group G1 and the intermediate group GM,between the intermediate group GM and the intermediate side lens groupGRP1, between the intermediate side lens group GRP1 and the subsequentside lens group GRP2, and between the subsequent side lens group GRP2and the subsequent group GR change (step ST2). The lens groups arearranged in the lens barrel so that the subsequent side lens group GRP2moves upon focusing (step ST3). The lens groups are arranged in the lensbarrel so that at least the conditional expression (1) described aboveis satisfied (step ST4).

EXAMPLES

Zoom optical systems (zoom lenses) ZL according to Examples of thepresent embodiment are described below with reference to the drawings.FIG. 1, FIG. 6, FIG. 11, FIG. 16, FIG. 21, and FIG. 26 arecross-sectional views illustrating configurations and refractive powerdistributions of the zoom optical systems ZL {ZL(1) to ZL(6)} accordingto Examples 1 to 6. In the lower portion of each cross-sectional view ofthe zoom optical systems ZL(1) to ZL(6), the directions in which thelens groups are moved along the optical axis upon zooming from the wideangle end state (W) to the telephoto end state (T) are shown by arrows.A direction in which the subsequent side lens group GRP2 serving as thefocusing lens group moves upon focusing on a short distant object frominfinity is shown by an arrow appended with “focusing”.

In FIGS. 1, 6, 11, 16, 21, and 26, a combination of a sign G and anumber represents each lens group, and a combination of a sign L and anumber represents each lens. In each Example, lens groups and the likeare each denoted with a combination of the reference sign and numeralindependently from other Examples to prevent cumbersomeness due to anexcessively wide variety or a large number of signs and numerals. Thus,components in different Examples denoted with the same combination ofreference sign and numeral does not necessarily have the sameconfiguration.

Tables 1 to 6 include Table 1 that is a specification table of Example1, Table 2 that is a specification table of Example 2, Table 3 that is aspecification table of Example 3, Table 4 that is a specification tableof Example 4, Table 5 that is a specification table of Example 5, andTable 6 that is a specification table of Example 6. In Examples, d-line(wavelength λ=587.6 nm) and g-line (wavelength λ=435.8 nm) are selectedas calculation targets of the aberration characteristics.

In Table [Lens specifications], a surface number represents an order ofan optical surface from the object side in a traveling direction of alight beam, R represents a radius of curvature of each optical surface(with a surface having the center of curvature position on the imageside provided with a positive value), D represents a distance betweeneach optical surface and the next optical surface (or the image surface)on the optical axis, nd represents a refractive index of a material ofan optical member with respect to the d-line, and νd represents an Abbenumber of the material of the optical member based on the d-line. In thetable, object surface represents an object surface, “∞” of the radius ofcurvature represents a plane or an aperture, (stop S) represents theaperture stop S, and image surface represents an image surface I. Therefractive index nd=1.00000 of air is omitted.

Specifically, in Table [Various data], f represents a focal length ofthe whole zoom lens, FNO represents F number, 2ω represents an angle ofview (w represents a half angle of view (unit: °)), and Ymax representsthe maximum image height. TL represents a distance obtained by adding BFto a distance between the lens forefront surface and a lens last surfaceon the optical axis upon focusing on infinity, and back focus (BF)represents a distance between the lens last surface and the imagesurface I on the optical axis upon focusing on infinity. These valuesare provided for each of the zooming states including the wide angle endstate (W), the intermediate focal length state (M), and the telephotoend state (T).

Table [Variable distance data] includes surface distances correspondingto surfaces corresponding to surface numbers appended with “variable” inTable [Lens specifications] and the next surface. The surface distancesare provided for each of the zooming states including the wide angle endstate (W), the intermediate focal length state (M), and the telephotoend state (T) upon focusing on infinity and upon focusing on a shortdistant object.

Table [Lens group data] includes the group starting surface (surfaceclosest to the object) and the focal length of each of the first to thefifth (or sixth) lens groups.

Table [Conditional expression corresponding value] represents valuescorresponding to the conditional expressions (1) to (5).

The focal length f, the radius of curvature R, the surface distance Dand the other units of length described below as all the specificationvalues, which are generally described with “mm” unless otherwise notedshould not be construed in a limiting sense because the optical systemproportionally expanded or reduced can have a similar or the sameoptical performance.

The description on the tables described above commonly applies to allExamples, and thus will not be redundantly given below.

Example 1

Example 1 is described with reference to FIG. 1, FIGS. 2A and 2B, FIG.3, FIGS. 4A and 4B, and FIGS. 5A-5C and Table 1. FIG. 1 is a diagramillustrating a lens configuration of a zoom optical system according toExample 1 of the present embodiment. The zoom optical system ZL(1)according to Example 1 consists of, in order from an object: a firstlens group G1 having positive refractive power; a second lens group G2having negative refractive power; a third lens group G3 having positiverefractive power; an aperture stop S; a fourth lens group G4 havingpositive refractive power; and a fifth lens group G5 having negativerefractive power. The first to the fifth lens groups G1 to G5 each movein a direction indicated by an arrow in FIG. 1 upon zooming from a wideangle end state (W) to a telephoto end state (T). In this Example, theintermediate group GM includes the second lens group G2, theintermediate side lens group GRP1 includes the third lens group G3 andthe aperture stop S, the subsequent side lens group GRP2 includes thefourth lens group G4, and the subsequent group GR includes the fifthlens group G5. A sign (+) or (−) provided to a sign of each lens grouprepresents refractive power of the lens group. The same applies to allof Examples described below.

The first lens group G1 consists of, in order from the object, apositive lens (1-1st lens) L11 having a biconvex shape and a cementedpositive lens consisting of a negative meniscus lens (1-2nd lens) L12having a convex surface facing the object and a positive meniscus lens(1-3rd lens) L13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object, anegative meniscus lens L21 having a convex surface facing the object, apositive meniscus lens L22 having a convex surface facing the object,and a cemented negative lens consisting of a negative lens L23 having abiconcave shape and a positive meniscus lens L24 having a convex surfacefacing the object.

The third lens group G3 consists of, in order from the object, apositive lens L31 having a biconvex shape and a cemented positive lensconsisting of a positive lens L32 having a biconvex shape and a negativelens L33 having a biconcave shape. The aperture stop S is disposed inthe neighborhood of and to the image side of the third lens group G3,and integrally moves with the third lens group G3 upon zooming.

The fourth lens group G4 consists of a cemented positive lens consistingof a positive lens L41 having a biconvex shape and a negative meniscuslens L42 having a concave surface facing the object.

The fifth lens group G5 consists of, in order from the object, anegative lens L51 having a biconcave shape, a positive meniscus lens L52having a concave surface facing the object, a negative meniscus lens L53having a concave surface facing the object, and a positive lens L54having a biconvex shape. An image surface I is disposed to the imageside of the fifth lens group G5.

In the zoom optical system ZL(1) according to Example 1, the fourth lensgroup G4 (subsequent side lens group GRP2) moves toward the object uponfocusing from a long distant object to a short distant object. In thezoom optical system ZL(1) according to Example 1, the cemented negativelens consisting of the negative lens L23 and the positive meniscus lensL24 in the second lens group G2 serves as a vibration-proof lens group,movable in a direction orthogonal to the optical axis, to be in chargeof correcting displacement of the imaging position due to camera shakeor the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the wholesystem being f and with a lens having a vibration proof coefficient K(the ratio of the image movement amount on the imaging surface to themovement amount of the moving lens group for camera shake correction), amoving lens group for camera shake correction is moved in the directionorthogonal to the optical axis by (f·tan θ)/K. In the wide angle endstate in Example 1, the vibration proof coefficient is 0.97 and thefocal length is 72.1 (mm), and thus the movement amount of thevibration-proof lens group to correct a roll blur of 0.30° is 0.39 (mm).In the telephoto end state in Example 1, the vibration proof coefficientis 2.01 and the focal length is 292.0 (mm), and thus the movement amountof the vibration-proof lens group to correct a roll blur of 0.20° is0.51 (mm).

Table 1 below lists specification values of the optical system accordingto Example 1.

TABLE 1 [Lens specifications] Surface number R D nd νd Object ∞ surface1 443.9646 3.817 1.48749 70.31 2 −469.6963 0.200 3 100.9381 1.7001.67270 32.19 4 64.8256 8.767 1.49700 81.73 5 2578.1121 Variable 6189.1236 1.000 1.77250 49.62 7 35.4799 7.123 8 37.2041 2.691 1.8051825.45 9 57.9432 4.513 10 −64.2854 1.000 1.67003 47.14 11 37.2626 3.5001.75520 27.57 12 146.7584 Variable 13 107.2202 3.817 1.80610 40.97 14−71.1994 0.200 15 41.9753 5.272 1.49700 81.73 16 −54.1569 1.000 1.8502632.35 17 154.3187 1.508 18 ∞ Variable (Aperture stop S) 19 104.18194.528 1.51680 63.88 20 −28.6539 1.000 1.80100 34.92 21 −53.7161 Variable22 −120.9949 1.000 1.90366 31.27 23 61.5584 10.276  24 −319.9239 4.0491.68893 31.16 25 −33.0322 16.448  26 −24.1471 1.000 1.77250 49.62 27−213.3380 0.200 28 79.7473 3.205 1.71736 29.57 29 −323.3417 BF Image ∞surface [Various data] Zooming rate 4.05 W M T f 72.1 99.9 292.0 FNO4.54 4.73 5.88 2ω 33.60 23.92 8.26 Ymax 21.60 21.60 21.60 TL 193.31211.69 248.31 BF 38.31 41.11 61.31 [Variable distance data] W M T W M TShort Short Short Infinity Infinity Infinity distant distant distant d52.000 26.394 73.625 2.000 26.394 73.625 d12 41.625 32.810 2.000 41.62532.810 2.000 d18 21.563 20.201 21.407 20.665 19.062 19.151 d21 2.0003.362 2.156 2.899 4.501 4.413 [Lens group data] Starting Focal Groupsurface length G1 1 169.064 G2 6 −41.090 G3 13 50.436 G4 19 100.808 G522 −52.611 [Conditional expression corresponding value] Conditionalexpression (1) f1/fRP1 = 3.352 Conditional expression (2) f1/(−fMt) =4.114 Conditional expression (3) fP/(−fN) = 0.564 Conditional expression(4) nP/nN = 0.895 Conditional expression (5) νP/νN = 2.539

FIG. 2A is a graph showing various aberrations of the zoom opticalsystem according to Example 1 having a vibration-proof function uponfocusing on infinity in the wide angle end state, and FIG. 2B is ameridional lateral aberration graph in a case where blur correction isperformed for the roll blur of 0.30°. FIG. 3 is a graph showing variousaberrations of the zoom optical system according to Example 1 having thevibration proof function upon focusing on infinity in the intermediatefocal length state. FIG. 4A is a graph showing various aberrations ofthe zoom optical system according to Example 1 having a vibration-prooffunction upon focusing on infinity in the telephoto end state, and FIG.4B is a meridional lateral aberration graph in a case where blurcorrection is performed for the roll blur of 0.20°. FIGS. 5A, 5B, and 5Care graphs showing various aberrations of the zoom optical systemaccording to Example 1 upon focusing on a short distant object,respectively in the wide angle end state, the intermediate focal lengthstate, and the telephoto end state.

In the aberration graphs in FIGS. 2A and 2B, FIG. 3, FIGS. 4A and 4B,and FIGS. 5A-5C, FNO denotes an F number, NA denotes the number ofapertures, and Y denotes an image height. The spherical aberrationgraphs illustrate an F number or the number of apertures correspondingto the maximum aperture, astigmatism graphs and distortion graphsillustrate the maximum image height, and coma aberration graphsillustrate values of image heights. d denotes a d line (wavelengthλ=587.6 mu) and g denotes a g line (wavelength λ=435.8 nm). In theastigmatism graphs, a solid line represents a sagittal image surface,and a broken line represents a meridional image surface. In aberrationgraphs in Examples described below, the same reference signs as in thisExample are used, and a redundant description is omitted.

It can be seen in these aberration graphs that the zoom optical systemaccording to Example 1 can achieve excellent imaging performance withvarious aberrations successfully corrected from the wide angle end stateto the telephoto end state, and can achieve excellent imagingperformance upon focusing on a short distant object.

Example 2

Example 2 is described with reference to FIG. 6, FIGS. 7A and 7B, FIG.8, FIGS. 9A and 9B, and FIGS. 10A-10C and Table 2. FIG. 6 is a diagramillustrating a lens configuration of a zoom optical system according toExample 2 of the present embodiment. The zoom optical system ZL(2)according to Example 2 consists of, in order from an object: a firstlens group G1 having positive refractive power; a second lens group G2having negative refractive power; a third lens group G3 having positiverefractive power; an aperture stop S; a fourth lens group G4 havingpositive refractive power; and a fifth lens group G5 having negativerefractive power. The first to the fifth lens groups G1 to G5 each movein a direction indicated by an arrow in FIG. 6 upon zooming from a wideangle end state (W) to a telephoto end state (T). In this Example, theintermediate group GM includes the second lens group G2, theintermediate side lens group GRP1 includes the third lens group G3 andthe aperture stop S, the subsequent side lens group GRP2 includes thefourth lens group G4, and the subsequent group GR includes the fifthlens group G5.

The first lens group G1 consists of, in order from the object, apositive lens (1-1st lens) L11 having a biconvex shape and a cementedpositive lens consisting of a negative meniscus lens (1-2nd lens) L12having a convex surface facing the object and a positive meniscus lens(1-3rd lens) L13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object, anegative meniscus lens L21 having a convex surface facing the object, anegative meniscus lens L22 having a concave surface facing the object, apositive meniscus lens L23 having a convex surface facing the object,and a cemented negative lens consisting of a negative lens L24 having abiconcave shape and a positive meniscus lens L25 having a convex surfacefacing the object.

The third lens group G3 consists of, in order from the object, apositive lens L31 having a biconvex shape and a cemented positive lensconsisting of a positive lens L32 having a biconvex shape and a negativelens L33 having a biconcave shape. The aperture stop S is disposed inthe neighborhood of and to the image side of the third lens group G3,and integrally moves with the third lens group G3 upon zooming.

The fourth lens group G4 consists of a cemented positive lens consistingof a positive lens L41 having a biconvex shape and a negative meniscuslens L42 having a concave surface facing the object.

The fifth lens group G5 consists of, in order from the object, anegative lens L51 having a biconcave shape, a positive lens L52 having abiconvex shape, a negative meniscus lens L53 having a concave surfacefacing the object, and a positive lens L54 having a biconvex shape. Animage surface I is disposed to the image side of the fifth lens groupG5.

In the zoom optical system ZL(2) according to Example 2, the fourth lensgroup G4 (subsequent side lens group GRP2) moves toward the object uponfocusing from a long distant object to a short distant object. In thezoom optical system ZL(2) according to Example 2, the cemented negativelens consisting of the negative lens L24 and the positive meniscus lensL25 in the second lens group G2 serves as a vibration-proof lens group,movable in a direction orthogonal to the optical axis, to be in chargeof correcting displacement of the imaging position due to camera shakeor the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the wholesystem being f and with a lens having a vibration proof coefficient K(the ratio of the image movement amount on the imaging surface to themovement amount of the moving lens group for camera shake correction), amoving lens group for camera shake correction is moved in the directionorthogonal to the optical axis by (f·tan θ)/K. In the wide angle endstate in Example 2, the vibration proof coefficient is 0.97 and thefocal length is 72.1 (mm), and thus the movement amount of thevibration-proof lens group to correct a roll blur of 0.30° is 0.39 (mm).In the telephoto end state in Example 2, the vibration proof coefficientis 2.03 and the focal length is 292.0 (mm), and thus the movement amountof the vibration-proof lens group to correct a roll blur of 0.20° is0.50 (mm).

Table 2 below lists specification values of the optical system accordingto Example 2.

TABLE 2 [Lens specifications] Surface number R D nd νd Object ∞ surface1 524.3080 3.649 1.48749 70.31 2 −473.1509 0.200 3 99.8647 1.700 1.6727032.19 4 65.5021 8.680 1.49700 81.73 5 1712.5853 Variable 6 93.5170 1.0001.83400 37.18 7 34.3474 6.920 8 −111.6255 1.000 1.60300 65.44 9−404.2382 0.200 10 45.6203 2.882 1.84666 23.80 11 103.2990 3.776 12−66.2945 1.000 1.70000 48.11 13 38.4320 3.453 1.79504 28.69 14 151.5709Variable 15 101.1563 3.699 1.80400 46.60 16 −81.9293 0.200 17 39.55955.119 1.49700 81.73 18 −67.2517 1.000 1.85026 32.35 19 148.7139 1.531 20∞ Variable (Aperture stop S) 21 99.6360 4.438 1.51680 63.88 22 −28.37551.000 1.80610 40.97 23 −55.9883 Variable 24 −69.2441 1.000 1.90366 31.2725 64.7455 7.965 26 1599.2908 4.469 1.67270 32.19 27 −30.6814 16.326  28−23.5416 1.000 1.80400 46.60 29 −175.4914 0.343 30 82.8193 3.436 1.6727032.19 31 −167.6215 BF Image ∞ surface [Various data] Zooming rate 4.05 WM T f 72.1 100.0 292.0 FNO 4.54 4.76 5.88 2ω 33.58 23.98 8.28 Ymax 21.6021.60 21.60 TL 193.32 210.95 248.32 BF 38.32 41.61 61.32 [Variabledistance data] W M T W M T Short Short Short Infinity Infinity Infinitydistant distant distant d5 2.000 25.989 75.552 2.000 25.989 75.552 d1443.552 33.897 2.000 43.552 33.897 2.000 d20 21.465 19.956 21.465 20.52718.788 19.123 d23 2.000 3.509 2.000 2.938 4.677 4.341 [Lens group data]Starting Focal Group surface length G1 1 173.986 G2 6 −42.714 G3 1549.108 G4 21 106.792 G5 24 −51.186 [Conditional expression correspondingvalue] Conditional expression (1) f1/fRP1 = 3.543 Conditional expression(2) f1/(−fMt) = 4.073 Conditional expression (3) fP/(−fN) = 0.596Conditional expression (4) nP/nN = 0.895 Conditional expression (5)νP/νN = 2.539

FIG. 7A is a graph showing various aberrations of the zoom opticalsystem according to Example 2 having a vibration-proof function uponfocusing on infinity in the wide angle end state, and FIG. 7B is ameridional lateral aberration graph in a case where blur correction isperformed for the roll blur of 0.30°. FIG. 8 is a graph showing variousaberrations of the zoom optical system according to Example 2 having avibration proof function upon focusing on infinity in the intermediatefocal length state. FIG. 9A is a graph showing various aberrations ofthe zoom optical system according to Example 2 having a vibration-prooffunction upon focusing on infinity in the telephoto end state, and FIG.9B is a meridional lateral aberration graph in a case where blurcorrection is performed for the roll blur of 0.20°. FIGS. 10A, 10B, and10C are graphs showing various aberrations of the zoom optical systemaccording to Example 2 upon focusing on a short distant object,respectively in the wide angle end state, the intermediate focal lengthstate, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical systemaccording to Example 2 can achieve excellent imaging performance withvarious aberrations successfully corrected from the wide angle end stateto the telephoto end state, and can achieve excellent imagingperformance upon focusing on a short distant object.

Example 3

Example 3 is described with reference to FIG. 11, FIGS. 12A and 12B,FIG. 13, FIGS. 14A and 14B, and FIGS. 15A-15C and Table 3. FIG. 11 is adiagram illustrating a lens configuration of a zoom optical systemaccording to Example 3 of the present embodiment. The zoom opticalsystem ZL(3) according to Example 3 consists of, in order from anobject: a first lens group G1 having positive refractive power; a secondlens group G2 having negative refractive power; a third lens group G3having positive refractive power; an aperture stop S; a fourth lensgroup G4 having positive refractive power; and a fifth lens group G5having negative refractive power. The first to the fifth lens groups G1to G5 each move in a direction indicated by an arrow in FIG. 11 uponzooming from a wide angle end state (W) to a telephoto end state (T). Inthis Example, the intermediate group GM includes the second lens groupG2, the intermediate side lens group GRP1 includes the third lens groupG3 and the aperture stop S, the subsequent side lens group GRP2 includesthe fourth lens group G4, and the subsequent group GR includes the fifthlens group G5.

The first lens group G1 consists of, in order from the object, apositive lens (1-1st lens) L11 having a biconvex shape and a cementedpositive lens consisting of a negative meniscus lens (1-2nd lens) L12having a convex surface facing the object and a positive meniscus lens(1-3rd lens) L13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object, anegative meniscus lens L21 having a convex surface facing the object, apositive meniscus lens L22 having a convex surface facing the object,and a cemented negative lens consisting of a negative lens L23 having abiconcave shape and a positive meniscus lens L24 having a convex surfacefacing the object.

The third lens group G3 consists of, in order from the object, apositive lens L31 having a biconvex shape and a cemented positive lensconsisting of a positive lens L32 having a biconvex shape and a negativelens L33 having a biconcave shape. The aperture stop S is disposed inthe neighborhood of and to the image side of the third lens group G3,and integrally moves with the third lens group G3 upon zooming.

The fourth lens group G4 consists of a cemented positive lens consistingof a positive lens L41 having a biconvex shape and a negative meniscuslens L42 having a concave surface facing the object.

The fifth lens group G5 consists of, in order from the object, anegative lens L51 having a biconcave shape, a negative lens L52 having abiconcave shape, a positive lens L53 having a biconvex shape, a negativemeniscus lens L54 having a concave surface facing the object, and apositive meniscus lens L55 having a convex surface facing the object. Animage surface I is disposed to the image side of the fifth lens groupG5.

In the zoom optical system ZL(3) according to Example 3, the fourth lensgroup G4 (subsequent side lens group GRP2) moves toward the object uponfocusing from a long distant object to a short distant object. In thezoom optical system ZL(3) according to Example 3, the cemented negativelens consisting of the negative lens L23 and the positive meniscus lensL24 in the second lens group G2 serves as a vibration-proof lens group,movable in a direction orthogonal to the optical axis, to be in chargeof correcting displacement of the imaging position due to camera shakeor the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the wholesystem being f and with a lens having a vibration proof coefficient K(the ratio of the image movement amount on the imaging surface to themovement amount of the moving lens group for camera shake correction), amoving lens group for camera shake correction is moved in the directionorthogonal to the optical axis by (f·tan θ)/K. In the wide angle endstate in Example 3, the vibration proof coefficient is 0.96 and thefocal length is 72.1 (mm), and thus the movement amount of thevibration-proof lens group to correct a roll blur of 0.30° is 0.39 (mm).In the telephoto end state in Example 3, the vibration proof coefficientis 1.99 and the focal length is 292.0 (mm), and thus the movement amountof the vibration-proof lens group to correct a roll blur of 0.20° is0.51 (mm).

Table 3 below lists specification values of the optical system accordingto Example 3.

TABLE 3 [Lens specifications] Surface number R D nd νd Object ∞ surface1 394.8396 3.845 1.48749 70.31 2 −543.4808 0.200 3 105.1984 1.7001.67270 32.19 4 67.0764 8.688 1.49700 81.73 5 3999.3650 Variable 6187.7927 1.000 1.83481 42.73 7 39.3002 8.392 8 40.6875 2.537 1.8466623.80 9 61.9560 4.302 10 −65.9607 1.000 1.70000 48.11 11 47.5227 2.9661.84666 23.80 12 155.3071 Variable 13 100.1220 3.921 1.80400 46.60 14−71.7118 0.200 15 39.6874 5.409 1.49700 81.73 16 −55.1551 1.000 1.8502632.35 17 138.4368 1.566 18 ∞ Variable (Aperture stop S) 19 90.1287 4.4301.51680 63.88 20 −29.8148 1.000 1.83400 37.18 21 −56.5509 Variable 22−89.4853 1.000 1.90366 31.27 23 58.7258 1.623 24 −119.8149 1.000 1.7725049.62 25 125.4243 2.815 26 86.3318 5.240 1.67270 32.19 27 −30.274518.277  28 −22.8447 1.000 1.80400 46.60 29 −60.6486 0.200 30 89.88912.703 1.66446 35.87 31 3303.4609 BF Image ∞ surface [Various data]Zooming rate 4.05 W M T f 72.1 99.9 292.0 FNO 4.53 4.71 5.88 2ω 33.5023.86 8.24 Ymax 21.60 21.60 21.60 TL 193.32 211.55 248.32 BF 38.32 41.1061.32 [Variable distance data] W M T W M T Short Short Short InfinityInfinity Infinity distant distant distant d5 2.000 26.748 74.901 2.00026.748 74.901 d12 42.901 33.607 2.000 42.901 33.607 2.000 d18 22.08620.598 21.608 21.186 19.465 19.388 d21 2.000 3.489 2.479 2.900 4.6214.698 [Lens group data]] Starting Focal Group surface length G1 1172.579 G2 6 −42.044 G3 13 48.716 G4 19 101.916 G5 22 −49.748[Conditional expression corresponding value] Conditional expression (1)f1/fRP1 = 3.543 Conditional expression (2) f1/(−fMt) = 4.105 Conditionalexpression (3) fP/(−fN) = 0.571 Conditional expression (4) nP/nN = 0.895Conditional expression (5) νP/νN = 2.539

FIG. 12A is a graph showing various aberrations of the zoom opticalsystem according to Example 3 having a vibration-proof function uponfocusing on infinity in the wide angle end state, and FIG. 12B is ameridional lateral aberration graph in a case where blur correction isperformed for the roll blur of 0.30°. FIG. 13 is a graph showing variousaberrations of the zoom optical system according to Example 3 having avibration proof function upon focusing on infinity in the intermediatefocal length state. FIG. 14A is a graph showing various aberrations ofthe zoom optical system according to Example 3 having a vibration-prooffunction upon focusing on infinity in the telephoto end state, and FIG.14B is a meridional lateral aberration graph in a case where blurcorrection is performed for the roll blur of 0.20°. FIGS. 15A, 15B, and15C are graphs showing various aberrations of the zoom optical systemaccording to Example 3 upon focusing on a short distant object,respectively in the wide angle end state, the intermediate focal lengthstate, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical systemaccording to Example 3 can achieve excellent imaging performance withvarious aberrations successfully corrected from the wide angle end stateto the telephoto end state, and can achieve excellent imagingperformance upon focusing on a short distant object.

Example 4

Example 4 is described with reference to FIG. 16, FIGS. 17A and 17B,FIG. 18, FIGS. 19A and 19B, and FIGS. 20A-20C and Table 4. FIG. 16 is adiagram illustrating a lens configuration of a zoom optical systemaccording to Example 4 of the present embodiment. The zoom opticalsystem ZL(4) according to Example 4 consists of, in order from anobject: a first lens group G1 having positive refractive power; a secondlens group G2 having negative refractive power; a third lens group G3having positive refractive power; an aperture stop S; a fourth lensgroup G4 having positive refractive power; and a fifth lens group G5having negative refractive power. The first to the fifth lens groups G1to G5 each move in a direction indicated by an arrow in FIG. 16 uponzooming from a wide angle end state (W) to a telephoto end state (T). Inthis Example, the intermediate group GM includes the second lens groupG2, the intermediate side lens group GRP1 includes the third lens groupG3 and the aperture stop S, the subsequent side lens group GRP2 includesthe fourth lens group G4, and the subsequent group GR includes the fifthlens group G5.

The first lens group G1 consists of, in order from the object, apositive lens (1-1st lens) L11 having a biconvex shape and a cementedpositive lens consisting of a negative meniscus lens (1-2nd lens) L12having a convex surface facing the object and a positive meniscus lens(1-3rd lens) L13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object, anegative meniscus lens L21 having a convex surface facing the object, apositive meniscus lens L22 having a convex surface facing the object,and a cemented negative lens consisting of a negative lens L23 having abiconcave shape and a positive meniscus lens L24 having a convex surfacefacing the object.

The third lens group G3 consists of, in order from the object, apositive lens L31 having a biconvex shape and a cemented positive lensconsisting of a positive lens L32 having a biconvex shape and a negativelens L33 having a biconcave shape. The aperture stop S is disposed inthe neighborhood of and to the image side of the third lens group G3,and integrally moves with the third lens group G3 upon zooming.

The fourth lens group G4 consists of, in order from the object, apositive lens L41 having a biconvex shape and a negative meniscus lensL42 having a concave surface facing the object.

The fifth lens group G5 consists of, in order from the object, anegative meniscus lens L51 having a convex surface facing the object, apositive meniscus lens L52 having a concave surface facing the object, anegative meniscus lens L53 having a concave surface facing the object,and a positive lens L54 having a biconvex shape. An image surface I isdisposed to the image side of the fifth lens group G5.

In the zoom optical system ZL(4) according to Example 4, the fourth lensgroup G4 (subsequent side lens group GRP2) moves toward the object uponfocusing from a long distant object to a short distant object. In thezoom optical system ZL(4) according to Example 4, the cemented negativelens consisting of the negative lens L23 and the positive meniscus lensL24 in the second lens group G2 serves as a vibration-proof lens group,movable in a direction orthogonal to the optical axis, to be in chargeof correcting displacement of the imaging position due to camera shakeor the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the wholesystem being f and with a lens having a vibration proof coefficient K(the ratio of the image movement amount on the imaging surface to themovement amount of the moving lens group for camera shake correction), amoving lens group for camera shake correction is moved in the directionorthogonal to the optical axis by (f·tan θ)/K. In the wide angle endstate in Example 4, the vibration proof coefficient is 0.99 and thefocal length is 72.1 (mm), and thus the movement amount of thevibration-proof lens group to correct a roll blur of 0.30° is 0.38 (mm).In the telephoto end state in Example 4, the vibration proof coefficientis 2.04 and the focal length is 292.0 (mm), and thus the movement amountof the vibration-proof lens group to correct a roll blur of 0.20° is0.50 (mm).

Table 4 below lists specification values of the optical system accordingto Example 4.

TABLE 4 [Lens specifications] Surface number R D nd νd Object ∞ surface1 397.7403 3.807 1.48749 70.31 2 −541.2704 0.200 3 98.5962 1.700 1.6727032.19 4 64.4142 7.530 1.49700 81.73 5 2167.3548 Variable 6 153.37591.000 1.80610 40.97 7 35.8256 8.557 8 37.5306 2.567 1.84666 23.80 955.0899 4.528 10 −64.5906 1.000 1.70000 48.11 11 45.3004 3.006 1.8466623.80 12 146.7719 Variable 13 120.3729 3.847 1.79952 42.09 14 −66.65530.200 15 40.5542 5.444 1.49700 81.73 16 −51.5427 1.000 1.85026 32.35 17136.7432 1.574 18 ∞ Variable (Aperture stop S) 19 73.0072 4.267 1.5168063.88 20 −41.6199 1.157 21 −36.8096 1.000 1.80100 34.92 22 −63.5855Variable 23 142.7978 1.000 1.90366 31.27 24 39.2858 5.972 25 −32.21732.394 1.80518 25.45 26 −25.4336 17.643  27 −22.2559 1.000 1.77250 49.6228 −60.4849 0.200 29 133.6379 3.767 1.69895 30.13 30 −86.4148 BF Image ∞surface [Various data] Zooming rate 4.05 W M T f 72.1 100.0 292.0 FNO4.58 4.77 5.88 2ω 33.52 23.92 8.28 Ymax 21.60 21.60 21.60 TL 193.32210.92 248.32 BF 38.32 41.32 62.32 [Variable distance data] W M T W M TShort Short Short Infinity Infinity Infinity distant distant distant d52.000 25.714 72.838 2.000 25.714 72.838 d12 41.838 32.720 2.000 41.83832.720 2.000 d18 24.804 23.298 24.804 23.943 22.207 22.596 d22 2.0003.505 2.000 2.861 4.597 4.208 [Lens group data] Starting Focal Groupsurface length G1 1 166.403 G2 6 −40.599 G3 13 52.091 G4 19 95.393 G5 23−58.282 [Conditional expression corresponding value] Conditionalexpression (1) f1/fRP1 = 3.194 Conditional expression (2) f1/(−fMt) =4.099 Conditional expression (3) fP/(−fN) = 0.468 Conditional expression(4) nP/nN = 0.895 Conditional expression (5) νP/νN = 2.539

FIG. 17A is a graph showing various aberrations of the zoom opticalsystem according to Example 4 having a vibration-proof function uponfocusing on infinity in the wide angle end state, and FIG. 17B is ameridional lateral aberration graph in a case where blur correction isperformed for the roll blur of 0.30°. FIG. 18 is a graph showing variousaberrations of the zoom optical system according to Example 4 having avibration proof function upon focusing on infinity in the intermediatefocal length state. FIG. 19A is a graph showing various aberrations ofthe zoom optical system according to Example 4 having a vibration-prooffunction upon focusing on infinity in the telephoto end state, and FIG.19B is a meridional lateral aberration graph in a case where blurcorrection is performed for the roll blur of 0.20°. FIGS. 20A, 20B, and20C are graphs showing various aberrations of the zoom optical systemaccording to Example 4 upon focusing on a short distant object,respectively in the wide angle end state, the intermediate focal lengthstate, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical systemaccording to Example 4 can achieve excellent imaging performance withvarious aberrations successfully corrected from the wide angle end stateto the telephoto end state, and can achieve excellent imagingperformance upon focusing on a short distant object.

Example 5

Example 5 is described with reference to FIG. 21, FIGS. 22A and 22B,FIG. 23, FIGS. 24A and 24B, and FIGS. 25A-25C and Table 5. FIG. 21 is adiagram illustrating a lens configuration of a zoom optical systemaccording to Example 5 of the present embodiment. The zoom opticalsystem ZL(5) according to Example 5 consists of, in order from anobject: a first lens group G1 having positive refractive power; a secondlens group G2 having negative refractive power; a third lens group G3having positive refractive power; an aperture stop S; a fourth lensgroup G4 having positive refractive power; a fifth lens group G5 havingnegative refractive power; and a sixth lens group G6 having negativerefractive power. The first to the sixth lens groups G1 to G6 each movein a direction indicated by an arrow in FIG. 21 upon zooming from a wideangle end state (W) to a telephoto end state (T). In this Example, theintermediate group GM includes the second lens group G2, theintermediate side lens group GRP1 includes the third lens group G3 andthe aperture stop S, the subsequent side lens group GRP2 includes thefourth lens group G4, and the subsequent group GR includes the fifthlens group G5 and the sixth lens group G6. The subsequent group GR hasnegative refractive power as a whole.

The first lens group G1 consists of, in order from the object, apositive lens (1-1st lens) L11 having a biconvex shape and a cementedpositive lens consisting of a negative meniscus lens (1-2nd lens) L12having a convex surface facing the object and a positive meniscus lens(1-3rd lens) L13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object, anegative meniscus lens L21 having a convex surface facing the object, apositive meniscus lens L22 having a convex surface facing the object,and a cemented negative lens consisting of a negative lens L23 having abiconcave shape and a positive meniscus lens L24 having a convex surfacefacing the object.

The third lens group G3 consists of, in order from the object, apositive lens L31 having a biconvex shape and a cemented positive lensconsisting of a positive lens L32 having a biconvex shape and a negativelens L33 having a biconcave shape. The aperture stop S is disposed inthe neighborhood of and to the image side of the third lens group G3,and integrally moves with the third lens group G3 upon zooming.

The fourth lens group G4 consists of, in order from the object, apositive lens L41 having a biconvex shape and a negative meniscus lensL42 having a concave surface facing the object.

The fifth lens group G5 consists of, in order from the object, anegative meniscus lens L51 having a convex surface facing the object anda positive meniscus lens L52 having a concave surface facing the object.

The sixth lens group G6 consists of, in order from the object, anegative meniscus lens L61 having a concave surface facing the objectand a positive lens L62 having a biconvex shape. An image surface I isdisposed to the image side of the sixth lens group G6.

In the zoom optical system ZL(5) according to Example 5, the fourth lensgroup G4 (subsequent side lens group GRP2) moves toward the object uponfocusing from a long distant object to a short distant object. In thezoom optical system ZL(5) according to Example 5, the cemented negativelens consisting of the negative lens L23 and the positive meniscus lensL24 in the second lens group G2 serves as a vibration-proof lens group,movable in a direction orthogonal to the optical axis, to be in chargeof correcting displacement of the imaging position due to camera shakeor the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the wholesystem being f and with a lens having a vibration proof coefficient K(the ratio of the image movement amount on the imaging surface to themovement amount of the moving lens group for camera shake correction), amoving lens group for camera shake correction is moved in the directionorthogonal to the optical axis by (f·tan θ)/K. In the wide angle endstate in Example 5, the vibration proof coefficient is 1.00 and thefocal length is 72.1 (mm), and thus the movement amount of thevibration-proof lens group to correct a roll blur of 0.30° is 0.38 (mm).In the telephoto end state in Example 5, the vibration proof coefficientis 2.07 and the focal length is 292.0 (mm), and thus the movement amountof the vibration-proof lens group to correct a roll blur of 0.20° is0.49 (mm).

Table 5 below lists specification values of the optical system accordingto Example 5.

TABLE 5 [Lens specifications] Surface number R D nd νd Object ∞ surface1 410.0484 3.688 1.48749 70.31 2 −563.1103 0.200 3 102.5753 1.7001.67270 32.19 4 66.0707 7.494 1.49700 81.73 5 15350.0260 Variable 6139.4435 1.000 1.80610 40.97 7 35.1229 7.231 8 37.6103 2.601 1.8466623.80 9 56.2791 4.573 10 −62.1771 1.000 1.70000 48.11 11 45.7876 3.0191.84666 23.80 12 152.3777 Variable 13 118.3464 3.864 1.79952 42.09 14−66.5127 0.200 15 41.1734 5.431 1.49700 81.73 16 −51.3614 1.000 1.8502632.35 17 129.2055 1.610 18 ∞ Variable (Aperture stop S) 19 79.6726 4.2631.51680 63.88 20 −41.5025 1.192 21 −36.1506 1.000 1.80100 34.92 22−57.7482 Variable 23 360.1366 1.000 1.90366 31.27 24 48.3936 6.817 25−37.2103 2.515 1.80518 25.45 26 −27.2408 Variable 27 −22.1710 1.0001.80400 46.60 28 −62.3440 0.200 29 129.8338 3.640 1.71736 29.57 30−94.8486 BF Image ∞ surface [Various data] Zooming rate 4.05 W M T f72.1 100.0 292.0 FNO 4.57 4.79 5.88 2ω 33.64 23.96 8.26 Ymax 21.60 21.6021.60 TL 193.32 211.43 248.32 BF 38.32 41.66 60.02 [Variable distancedata] W M T W M T Short Short Short Infinity Infinity Infinity distantdistant distant d5 2.000 25.563 73.573 2.000 25.563 73.573 d12 42.57333.490 2.000 42.573 33.490 2.000 d18 24.947 23.743 24.947 24.097 22.67422.767 d22 2.000 3.203 2.000 2.849 4.273 4.180 d26 17.243 17.537 19.54417.243 17.537 19.544 [Lens group data] Starting Focal Group surfacelength G1 1 168.635 G2 6 −41.024 G3 13 53.154 G4 19 92.760 G5 23−175.236 G6 27 −106.197 [Conditional expression corresponding value]Conditional expression (1) f1/fRP1 = 3.173 Conditional expression (2)f1/(−fMt) = 4.111 Conditional expression (3) fP/(−fN) = 0.434Conditional expression (4) nP/nN = 0.895 Conditional expression (5)νP/νN = 2.539

FIG. 22A is a graph showing various aberrations of the zoom opticalsystem according to Example 5 having a vibration-proof function uponfocusing on infinity in the wide angle end state, and FIG. 22B is ameridional lateral aberration graph in a case where blur correction isperformed for the roll blur of 0.30°. FIG. 23 is a graph showing variousaberrations of the zoom optical system according to Example 5 having avibration proof function upon focusing on infinity in the intermediatefocal length state. FIG. 24A is a graph showing various aberrations ofthe zoom optical system according to Example 5 having a vibration-prooffunction upon focusing on infinity in the telephoto end state, and FIG.24B is a meridional lateral aberration graph in a case where blurcorrection is performed for the roll blur of 0.20°. FIGS. 25A, 25B, and25C are graphs showing various aberrations of the zoom optical systemaccording to Example 5 upon focusing on a short distant object,respectively in the wide angle end state, the intermediate focal lengthstate, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical systemaccording to Example 5 can achieve excellent imaging performance withvarious aberrations successfully corrected from the wide angle end stateto the telephoto end state, and can achieve excellent imagingperformance upon focusing on a short distant object.

Example 6

Example 6 is described with reference to FIG. 26, FIGS. 27A and 27B,FIG. 28, FIGS. 29A and 29B, and FIGS. 30A-30C and Table 6. FIG. 26 is adiagram illustrating a lens configuration of a zoom optical systemaccording to Example 6 of the present embodiment. The zoom opticalsystem ZL(6) according to Example 6 consists of, in order from anobject: a first lens group G1 having positive refractive power; a secondlens group G2 having negative refractive power; a third lens group G3having negative refractive power; a fourth lens group G4 having positiverefractive power; an aperture stop S; a fifth lens group G5 havingpositive refractive power; and a sixth lens group G6 having negativerefractive power. The first to the sixth lens groups G1 to G6 each movein a direction indicated by an arrow in FIG. 26 upon zooming from a wideangle end state (W) to a telephoto end state (T). In this Example, theintermediate group GM includes the second lens group G2 and the thirdlens group G3, the intermediate side lens group GRP1 includes the fourthlens group G4 and the aperture stop S, the subsequent side lens groupGRP2 includes the fifth lens group G5, and the subsequent group GRincludes the sixth lens group G6. The intermediate group GM has negativerefractive power as a whole.

The first lens group G1 consists of, in order from the object, apositive lens (1-1st lens) L11 having a biconvex shape and a cementedpositive lens consisting of a negative meniscus lens (1-2nd lens) L12having a convex surface facing the object and a positive meniscus lens(1-3rd lens) L13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object, anegative meniscus lens L21 having a convex surface facing the object anda positive meniscus lens L22 having a convex surface facing the object.

The third lens group G3 consists of a cemented negative lens consistingof a negative lens L31 having a biconcave shape and a positive meniscuslens L32 having a convex surface facing the object.

The fourth lens group G4 consists of, in order from the object, apositive lens L41 having a biconvex shape and a cemented positive lensconsisting of a positive lens L42 having a biconvex shape and a negativelens L43 having a biconcave shape. The aperture stop S is disposed inthe neighborhood of and to the image side of the fourth lens group G4,and integrally moves with the fourth lens group G4 upon zooming.

The fifth lens group G5 consists of a cemented positive lens consistingof a positive lens L51 having a biconvex shape and a negative meniscuslens L52 having a concave surface facing the object.

The sixth lens group G6 consists of, in order from the object, anegative lens L61 having a biconcave shape, a positive meniscus lens L62having a concave surface facing the object, a negative meniscus lens L63having a concave surface facing the object, and a positive lens L64having a biconvex shape. An image surface I is disposed to the imageside of the sixth lens group G6.

In the zoom optical system ZL(6) according to Example 6, the fifth lensgroup G5 (subsequent side lens group GRP2) moves toward the object uponfocusing from a long distant object to a short distant object. In thezoom optical system ZL(6) according to Example 6, the third lens groupG3 serves as a vibration-proof lens group, movable in a directionorthogonal to the optical axis, to be in charge of correctingdisplacement of the imaging position due to camera shake or the like(image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the wholesystem being f and with a lens having a vibration proof coefficient K(the ratio of the image movement amount on the imaging surface to themovement amount of the moving lens group for camera shake correction), amoving lens group for camera shake correction is moved in the directionorthogonal to the optical axis by (f·tan θ)/K. In the wide angle endstate in Example 6, the vibration proof coefficient is 0.97 and thefocal length is 72.1 (mm), and thus the movement amount of thevibration-proof lens group to correct a roll blur of 0.30° is 0.39 (mm).In the telephoto end state in Example 6, the vibration proof coefficientis 2.01 and the focal length is 292.0 (mm), and thus the movement amountof the vibration-proof lens group to correct a roll blur of 0.20° is0.51 (mm).

Table 6 below lists specification values of the optical system accordingto Example 6.

TABLE 6 [Lens specifications] Surface number R D nd νd Object ∞ surface1 508.9189 3.766 1.48749 70.31 2 −429.0392 0.200 3 100.5086 1.7001.67270 32.19 4 64.9622 8.695 1.49700 81.73 5 2159.2215 Variable 6177.6966 1.000 1.83481 42.73 7 35.6714 6.299 8 37.8917 2.779 1.8466623.80 9 62.3935 Variable 10 −64.2559 1.000 1.67003 47.14 11 36.71453.536 1.75520 27.57 12 146.9123 Variable 13 109.3840 3.810 1.80610 40.9714 −70.8019 0.200 15 42.2948 5.265 1.49700 81.73 16 −53.8261 1.0001.85026 32.35 17 161.9717 1.485 18 ∞ Variable (Aperture stop S) 19106.0675 4.532 1.51680 63.88 20 −28.5067 1.000 1.80100 34.92 21 −53.2383Variable 22 −126.6137 1.000 1.90366 31.27 23 60.3618 10.455  24−323.4470 4.054 1.68893 31.16 25 −33.1410 16.327  26 −24.3740 1.0001.77250 49.62 27 −200.9248 0.200 28 79.6785 3.126 1.71736 29.57 29−428.7833 BF Image ∞ surface [Various data] Zooming rate 4.05 W M T f72.1 100.0 292.0 FNO 4.54 4.72 5.88 2ω 33.58 23.90 8.26 Ymax 21.60 21.6021.60 TL 193.32 211.83 248.32 BF 38.32 41.01 61.32 [Variable distancedata] W M T W M T Short Short Short Infinity Infinity Infinity distantdistant distant d5 2.000 26.835 74.493 2.000 26.835 74.493 d9 5.4005.100 4.500 5.400 5.100 4.500 d12 41.592 32.879 2.000 41.592 32.8792.000 d18 21.578 20.267 21.578 20.680 19.126 19.320 d21 2.000 3.3112.001 2.898 4.453 4.259 [Lens group data] Starting Focal Group surfacelength G1 1 170.267 G2 6 −114.490 G3 10 −74.908 G4 13 50.411 G5 19100.849 G6 22 −52.429 [Conditional expression corresponding value]Conditional expression (1) f1/fRP1 = 3.378 Conditional expression (2)f1/(−fMt) = 4.107 Conditional expression (3) fP/(−fN) = 0.564Conditional expression (4) nP/nN = 0.895 Conditional expression (5)νP/νN = 2.539

FIG. 27A is a graph showing various aberrations of the zoom opticalsystem according to Example 6 having a vibration-proof function uponfocusing on infinity in the wide angle end state, and FIG. 27B is ameridional lateral aberration graph in a case where blur correction isperformed for the roll blur of 0.30°. FIG. 28 is a graph showing variousaberrations of the zoom optical system according to Example 6 having avibration proof function upon focusing on infinity in the intermediatefocal length state. FIG. 29A is a graph showing various aberrations ofthe zoom optical system according to Example 6 having a vibration-prooffunction upon focusing on infinity in the telephoto end state, and FIG.29B is a meridional lateral aberration graph in a case where blurcorrection is performed for the roll blur of 0.20°. FIGS. 30A, 30B, and30C are graphs showing various aberrations of the zoom optical systemaccording to Example 6 upon focusing on a short distant object,respectively in the wide angle end state, the intermediate focal lengthstate, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical systemaccording to Example 6 can achieve excellent imaging performance withvarious aberrations successfully corrected from the wide angle end stateto the telephoto end state, and can achieve excellent imagingperformance upon focusing on a short distant object.

According to Examples described above, the subsequent side lens groupGRP2 serves as the focusing lens group to achieve a small size and lightweight so that quick and quiet AF can be implemented without using alarge barrel. Furthermore, a zoom optical system successfully preventingvariation of aberrations upon zooming from the wide angle end state tothe telephoto end state, as well as variation of aberrations uponfocusing on a short distant object from an infinite distant object canbe implemented.

Examples described above are merely examples of the invention accordingto the present application. The invention according to the presentapplication is not limited to these examples.

The following configurations can be appropriately employed as long asthe optical performance of the zoom optical system according to thepresent embodiment is not compromised.

Examples of values of the zoom optical system according the presentembodiment having five or six lens groups are described above. However,this should not be construed in a limiting sense, and a zoom opticalsystem with other lens group configurations (for example, aconfiguration with seven lens groups or the like) may be employed. Morespecifically, the zoom optical system according to the presentembodiment may be further provided with a lens or a lens group closestto an object or further provided with a lens or a lens group closest tothe image surface. The lens group is a portion comprising at least onelens separated from another lens with a distance varying upon zooming.

The focusing lens group is a portion comprising at least one lensseparated from another lens with a distance varying upon focusing. Thus,the focusing lens group may be provided for focusing from an infinitedistant object to a short distant object, with a single or a pluralityof lens groups or a partial lens group moved in the optical axisdirection. The focusing lens group can be applied to auto focus, and issuitable for motor driving for auto focus (using supersonic wave motors,etc.).

The lens surface may be formed to have a spherical surface or a planersurface, or may be formed to have an aspherical surface. The lenssurface having a spherical surface or a planer surface features easylens processing and assembly adjustment, which leads to the processingand assembly adjustment less likely to involve an error compromising theoptical performance, and thus is preferable. Furthermore, there is anadvantage that a rendering performance is not largely compromised evenwhen the image surface is displaced.

The lens surface having an aspherical surface may be achieved with anyone of an aspherical surface formed by grinding, a glass-moldedaspherical surface obtained by molding a glass piece into an asphericalshape, and a composite type aspherical surface obtained by providing anaspherical shape resin piece on a glass surface. A lens surface may be adiffractive surface. The lens may be a gradient index lens (GRIN lens)or a plastic lens.

The aperture stop is preferably disposed in the neighborhood of thethird or the fourth lens group. Alternatively, the aperture stop may bedisposed in the third or the fourth lens group. A lens frame may serveas the aperture stop so that the member serving as the aperture stopneeds not to be provided.

The lens surfaces may be provided with an antireflection film comprisinghigh transmittance over a wide range of wavelengths to achieve anexcellent optical performance with reduced flare and ghosting andincreased contrast. Thus, an excellent optical performance with reducedflare and ghosting and increased contrast can be achieved.

EXPLANATION OF NUMERALS AND CHARACTERS

G1 first lens group G2 second lens group G3 third lens group G4 fourthlens group G5 fifth lens group G6 sixth lens group GM intermediate groupGR subsequent group GRP1 intermediate side lens group GRP2 subsequentside lens group I image surface S aperture stop

1. A zoom optical system comprising, in order from an object: a firstlens group having positive refractive power; an intermediate groupincluding at least one lens group and having negative refractive poweras a whole; an intermediate side lens group having positive refractivepower; a subsequent side lens group having positive refractive power;and a subsequent group including at least one lens group, wherein uponzooming, distances between the first lens group and the intermediategroup, between the intermediate group and the intermediate side lensgroup, between the intermediate side lens group and the subsequent sidelens group, and between the subsequent side lens group and thesubsequent group change, the subsequent side lens group moves uponfocusing, and a following conditional expression is satisfied:2.5<f1/fRP1<5.0 where, f1 denotes a focal length of the first lensgroup, and fRP1 denotes a focal length of the intermediate side lensgroup.
 2. The zoom optical system according to claim 1, wherein theintermediate group comprises a vibration-proof lens group movable tohave a component in a direction orthogonal to an optical axis to correctimage blur.
 3. The zoom optical system according to claim 1, wherein afollowing conditional expression is satisfied:2.9<f1/(−fMt)<5.5 where, fMt denotes a focal length of the intermediategroup in the telephoto end state.
 4. The zoom optical system accordingto claim 1, wherein the first lens group moves toward the object uponzooming from a wide angle end state to a telephoto end state.
 5. Thezoom optical system according to claim 1, wherein the subsequent sidelens group comprises at least one lens having positive refractive powerand at least one lens having negative refractive power.
 6. The zoomoptical system according to claim 5, wherein a following conditionalexpression is satisfied:0.2<fP/(−fN)<0.8 where, fP denotes a focal length of a lens with largestpositive refractive power in the subsequent side lens group, and fNdenotes a focal length of a lens with largest negative refractive powerin the subsequent side lens group.
 7. The zoom optical system accordingto claim 1, wherein the first lens group comprises, in order from anobject: a 1-1st lens having positive refractive power; a 1-2nd lenshaving negative refractive power; and a 1-3rd lens having positiverefractive power.
 8. The zoom optical system according to claim 7,wherein a following conditional expression is satisfied:0.85<nP/nN<1.00 where, nP denotes a refractive index of a lens withlargest positive refractive power in the first lens group, and nNdenotes a refractive index of a lens with largest negative refractivepower in the first lens group.
 9. The zoom optical system according toclaim 7, wherein a following conditional expression is satisfied:2.25<νP/νN<2.90 where, νP denotes an Abbe number of the lens withlargest positive refractive power in the first lens group, and νNdenotes an Abbe number of the lens with largest negative refractivepower in the first lens group.
 10. An optical apparatus comprising thezoom optical system according to claim
 1. 11. A method for manufacturinga zoom optical system which comprises, in order from an object: a firstlens group having positive refractive power; an intermediate groupincluding at least one lens group and having negative refractive poweras a whole; an intermediate side lens group having positive refractivepower; a subsequent side lens group having positive refractive power;and a subsequent group including at least one lens group, the methodcomprising a step of arranging the lens groups in a lens barrel so that:upon zooming, distances between the first lens group and theintermediate group, between the intermediate group and the intermediateside lens group, between the intermediate side lens group and thesubsequent side lens group, and between the subsequent side lens groupand the subsequent group change; the subsequent side lens group movesupon focusing; and a following conditional expression is satisfied:2.5<f1/fRP1<5.0 where, f1 denotes a focal length of the first lensgroup, and fRP1 denotes a focal length of the intermediate side lensgroup.